Caracterização do comportamento reológico e determinação de propriedades termofísicas de polpa de manga Ubá

• Autor(a) principal: Diniz, Mayra Darliane Martins Silva
• Data de Publicação: 2009
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/2868
• topic: Densidade; Difusividade térmica; Viscosidade; Temperatura; Concentração; Density; Thermal diffusivity; Viscosity; Temperature; Concentration; CNPQ::CIENCIAS AGRARIAS::CIENCIA E TECNOLOGIA DE ALIMENTOS::TECNOLOGIA DE ALIMENTOS

The fruits, in general, are perishable, which gives them a short self-life in the market for fruit in natura. This will require the need for industrialization of theses foods for production of derivatives. The potential for strong growth and continued market of the derived juices of the fruit appears in the future as a fact safe. The acquisition of physical properties of foods is of fundamental importance for the analysis of problems found in the basic operations of the industries of foods. There is a growing need and demand of the rheological parameters and thermophysical properties for different fluids handled in the industries of foods. This study aimed to investigate the physicochemical characteristics, density, thermal diffusivity and rheological properties of Ubá mango pulp at different temperatures (10, 25, 40, 55, 70) ° C and different concentrations (5, 10, 15, 25 , 30) ° Brix. The acquired mango pulp presented thefollowing physicochemical characteristics: pH: 4.05 ± 0.11, acidity: 0.37% citric acid, (16.0 ± 0.29) ° Brix, moisture: 82,17%, total sugar: 10.59 (% glucose). The experimental data for the density and the thermal diffusivity were close to those reported in the literature. The models proposed provided settings, with percentage errors between 0.03% and 35%. The Ubá mango pulp showed thixotropic behavior only in concentrations (25 and 30) ° Brix for range of temperature studied. The model proposed by Figoni & Shoemaker was the best fit to the experimental data. The parameters &#964; e - &#964; o (number of structures damaged during shear) and Ki (structural degradation rate) were obtained to thixotropic characterization. The Herschel-Bulkley model adequately describes the rheological behavior of Ubá mango pulp. The values of yield stress (&#964; o), consistency coefficient (KH), flow behavior index (nH) and apparent viscosity (&#951;) at shear rate of 100 s-1 were determined. The values of the parameters ers (&#964; &#8722;&#964; e 0 ), 0 &#964; and a &#951; increased with the concentration of soluble solids of the pulp. The parameters obtained for the study of the thixotropic and flow behavior of the Ubá mango pulp were significant (p <0.0001). Also was studied the effect of temperature, concentration and the combined effect of temperature and concentration on rheological behavior of Ubá mango pulp. It was observed that the shear stress decreased with increasing temperature and there was a trend of apparent viscosity decrease with increasing temperature and increasing the apparent viscosity in the samples with levels of soluble solids higher.